The electronics industry has long recognized the need for a package to house an integrated circuit chip with a relatively large number of input and output leads or pins, for example, from 48 to 120 pins. A number of approaches to this problem have been attempted. For example, the conventional dual inline package (DIP) has been expanded to accommodate up to 64 leads. However, because of the large package size, its use with high speed circuits introduces unwanted signal delays and added capacitance. Additionally, the large DIP package exhibits poor thermal characteristics.
Other packages currently used in the industry for high density circuit configurations place the input/output pins on the bottom surface thereof. In such packages, the integrated circuit chip is mounted in proximity to the last mentioned surface such that the heat generated in the package must ordinarily be dissipated through the pins. From a thermal standpoint, this arrangement is highly inefficient. Moreover, in at least one such design, the permissible number of input/output pins is sacrificed to provide a chip mounting area.
Considerable effort is presently being expended in complicated and often cumbersome techniques for providing a low thermal resistance path between the integrated circuit chip mounted generally in proximity to the pin-carrying substrate and a cooling medium. The following articles appearing in the IBM Technical Disclosure Bulletin are representative of such effort: Vol. 22, No. 4, September 1979, "Module Package with Heat Sink Between Substrate and Circuit Board", by H. D. Stackhouse in which heat dissipation is through the input/output pins and the heat sink; Vol. 22, No. 1, June 1979, "Air and Liquid Drop Cooled Module", by J. R. Lynch where a heat conductive fluid is interposed between the chip and the package cap; Vol. 22, No. 1, June 1979, "Module Heat Pipe Cooling Structure"0 by B. V. Gokhale, et al., where a thermal path is provided by pipe wicks which are placed in contact with the chips; Vol. 21, No. 8, January 1979, "Self-Regulating Evaporative/Conductive Thermal Link" By K. P. Moran and R. E. Simons, in which a sealed flexible spring-like bellows and an internal wetted wick provide an improved thermal path from the chip to the primary coolant; Vol. 21, No. 8, January 1979, "Thermal Conductive Piston for Semiconductor Packages" by L. Landstein, which includes a spring-loaded slidable piston in contact with the chip to minimize thermal resistance.
The integrated circuit package described hereinafter obviates the problems inherent in present day packaging and provides in effect, both a high density of input/output connections and the thermal efficiency to dissipate the increased power associated therewith.